Understand the probability
What the expected value decision calculator is calculating
Connecting outcomes, probabilities, and long-run value. A discrete random variable assigns a numerical value to every possible outcome. Its distribution supports expected value and variance, but an expectation is a long-run average—not a guaranteed single outcome.
1Pair every value with its probability2Confirm probabilities form a complete model3Weight values or squared deviations and add
Probability rule
Net EV=Σpᵢxᵢ−fixed cost; binary break-even success probability=(cost−failure outcome)/(success−failure).
Every probability must remain between 0 and 1, and overlapping regions must be jointly feasible. The calculator rejects combinations that violate the stated model.
How to interpret it
Higher expected value does not automatically dominate when downside, liquidity, risk tolerance, or nonfinancial consequences differ.
Model boundary: Each option’s probabilities must total one; monetary or utility values must use a common scale and fixed costs apply in every outcome.
Quick guide
How to use this calculator
- Enter the observations, probabilities, model parameters, or summary statistics requested by the visible labels.
- Keep every value on the same scale and confirm that the selected sampling relationship, distribution, and tail convention match the question you are investigating.
- Read the result together with its assumptions and interpretation. Statistical output summarizes uncertainty under a model; it does not repair biased data or establish causation.
Calculation method
How the expected value decision calculator works
Net EV=Σpᵢxᵢ−fixed cost; binary break-even success probability=(cost−failure outcome)/(success−failure).
Higher expected value does not automatically dominate when downside, liquidity, risk tolerance, or nonfinancial consequences differ.
Worked example
Expected Value Decision example
A 40% chance of 100 and 60% chance of 0 with cost 25 has net expected value 15 and break-even success probability 25%.
Net EV=Σpᵢxᵢ−fixed cost; binary break-even success probability=(cost−failure outcome)/(success−failure).
Supported inputs
Precision and limits
Model and design
Each option’s probabilities must total one; monetary or utility values must use a common scale and fixed costs apply in every outcome.
Numerical scope
Inputs use double-precision numerical methods with guarded domains. Datasets accept up to 10,000 finite plain-decimal values. Extremely large parameters or probabilities deep in a numerical tail may require specialist statistical software.
Interpretation
Higher expected value does not automatically dominate when downside, liquidity, risk tolerance, or nonfinancial consequences differ.
Decision boundary
The calculator does not validate how data were collected, diagnose dependence or bias, choose a scientifically meaningful effect, or replace review by a qualified statistician for consequential research, medical, regulatory, safety, or policy decisions.
Privacy
Entered values and calculated results stay in this browser and are not sent to an analytics service.
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